1. Field of the Invention
This invention relates generally to devices and techniques for performing cardiac procedures and particularly a catheter system and methods for inducing cardioplegic arrest to facilitate the performance of cardiac procedures.
2. The Related Technology
Known techniques for performing major surgeries such as coronary artery bypass grafting and heart valve repair and replacement have generally required open access to the thoracic cavity through a large open wound, known as a thoracotomy. Typically, the sternum is cut longitudinally (i.e., a median sternotomy), providing access between opposing halves of the anterior portion of the rib cage to the heart and other thoracic vessels and organs. An alternate method of entering the chest is via a lateral thoracotomy, in which an incision, typically 10 cm to 20 cm in length, is made between two ribs. A portion of one or more ribs may be permanently removed to optimize access.
In procedures requiring a median sternotomy or other type of thoracotomy, the ascending aorta is readily accessible for placement of an external cross-clamp, and for introduction of a cardioplegic fluid delivery cannula and venting cannula through the aortic wall. However, such surgery often entails weeks of hospitalization and months of recuperation time, in addition to the pain and trauma suffered by the patient. Moreover, while the average mortality rate associated with this type of procedure is about two to fifteen percent for first-time surgery, mortality and morbidity are significantly increased for reoperation. Further, significant complications may result from such procedures. For example, application of an external cross-clamp to a calcified or atheromatous aorta may cause the release of emboli into the brachiocephalic, carotid or subclavian arteries with serious consequences such as strokes.
A less invasive surgical approach is preferred as an alternative to open-chest surgery. During a minimally invasive surgical procedure, a surgeon may access a body lumen such as the femoral artery or jugular, and extend one or more elements through the vasculature of the patient so as to access a location remote from the access window. Devices that may be extended through the access window and to a location of the surgical procedure include catheters, stents, guidewires, or other surgical devices that may be inserted through such an access window for a procedure remote from the access window itself. Thus, a variety of surgical procedures may be performed within the cavities of the body, particularly including minimally invasive and less invasive surgical procedures in which surgical instruments are introduced through an access window, and then extended through body lumens to a desired location.
Methods and devices are therefore needed for isolating the heart and coronary arteries from the remainder of the arterial system, arresting cardiac function, and establishing cardiopulmonary bypass without the open-chest access provided by a median sternotomy or other type of thoracotomy. In particular, methods and devices are needed which facilitate the delivery of retrograde cardioplegia sufficiently to allow the heart to be placed under cardioplegic arrest with full cardiopulmonary bypass, without requiring open-chest access to the heart and without requiring an incision or puncture in the aorta, in the pulmonary artery, or in the heart wall. Embodiments of the present disclosure satisfy these and other needs.